Creating 3D objects presents particular challenges both in terms of the complexity of modeling 3D objects and of generating 3D objects to accurately portray real-life objects. Many 3D printers or additive manufacturing devices print or generate objects from 3D models generated from computer aided design (CAD) applications, for example, by slicing the model into thin horizontal layers and depositing material (e.g., melted plastic, clay, concrete, metal powder, food stuff) vertically layer by layer. The layer height (thickness) is typically selected through a user interface (UI) control that allows either direct, fixed setting of layer height (e.g., 0.25 mm or 250 microns) or setting layer resolution in a simpler, general form with predetermined layer heights associated with standard printer terms (e.g., Fine, Normal, Draft, etc.). The layer height or layer resolution is closely linked to the tradeoff between print speed vs. vertical step resolution print quality. Contemporary slicing application software (slicers) generally fails to consider the impact that a fixed layer height has on the printed object's overall vertical dimension accuracy. Quantization in the form of fixed-height layer slices can result in vertical (z-axis) dimension errors of +− 50% of the selected layer height (e.g., 0.125 mm for a 0.25 mm layer height), two orders of magnitude over the typical x-y plane dimensional accuracy of 2 microns (0.002 mm) that can typically be produced by a well-adjusted 3D printer.
As a result of blind selection of layer height, 3D printed objects end up having vertical or z-axis features (including the top of the object) aligned to a multiple of the selected layer height and having a potentially large error in the printed object's z-dimension. For example, printing a 1.12 mm 3D object with a 250 micron layer will result in a 1 mm tall object in practice, or a 12% error. This error occurs because the object would require 4.48 layers, but the slicer rounds down to 4 layers. The error effects are not limited to the top of the object, but to all the object's features at different z layer heights. For example, consider the case of printing a stair object where the step increments do not align with the layer heights. This configuration results in errors at each step along the way to the object's upper surface. Generally controlled by stepper or servo motors, or other movement means, 3D printer hardware is capable of much higher precision on the Z axis—typically in the range of 10 microns to less than 1 micron (100 steps/mm-1600 steps/mm) resolution in practice. This fine positioning control in the z-axis hardware creates a theoretical opportunity to produce objects with z dimensional accuracy to within 1-10 microns (0.1 to 1% error). Accordingly, improvements to 3D printing processes can be made.